Herein are disclosed photosensitive members, photoreceptors, or photoconductors useful in electrostatographic apparatuses, including printers, copiers, other reproductive devices, and digital apparatuses. In specific embodiments, the photoreceptors comprise a two-layer undercoat, which, in embodiments, comprises an electroconducting layer having an interfacial layer thereon. In embodiments, an electroconducting particle is dispersed or contained in one or more layers of the photosensitive member, such as, for example, the electroconducting layer. In embodiments, the electroconducting particle comprises an inert core and a conductive shell. In embodiments, the inert core comprises a silica, mica or titania, and the conductive shell comprises a metal oxide or a doped metal oxide. In embodiments, the doped metal oxide is antimony-doped tin oxide.
Electrophotographic imaging members, including photoreceptors or photoconductors, typically include a photoconductive layer formed on an electrically conductive substrate or formed on layers between the substrate and photoconductive layer. The photoconductive layer is an insulator in the dark, so that electric charges are retained on its surface. Upon exposure to light, the charge is dissipated, and an image can be formed thereon, developed using a developer material, transferred to a copy substrate, and fused thereto to form a copy or print.
Thick undercoat layer is desirable for photoreceptor life extension. In addition, thick undercoat layer does not demand high-quality substrate, thus enabling cheap substrates for low cost. Furthermore, a thick undercoat layer can prevent foreign material such as carbon fiber penetration into a photoreceptor, thus eliminating problem referred to as color spot. A one-layer thick undercoat is most desirable from a manufacturing standpoint. However, development of a one-layer thick undercoat is more difficult since there is a conflicting requirement associated with one-layer thick undercoats. Lower undercoat layer (UCL) resistivity is desired for efficient electron transport, and therefore, a lower residual potential for high thickness is desired. However, a lower UCL resistivity usually causes Vhigh cycle down and charge deficient spots (CDS), which limit photoreceptor cycle time. Therefore, a two-layer undercoat concept is desired, since it separates hole-blocking function caused by a thin interfacial layer, and prevents foreign material penetration brought by a thick electroconducting layer. However, a two-layer design may be unfavorable from a manufacturing standpoint.
Therefore, there exists a need in the art for an improved photosensitive member. Desired is a photoreceptor having humidity-independent performance, excellent durability, and the ability to achieve a wide range of surface electrical resistivity (SER). In addition, it is desired to provide an undercoat layer system that is relatively easy to make. Moreover, it is desired to provide an undercoat system with plywood suppression. Further, improved dispersion quality is desired.
The photoreceptor herein comprises a two-layer undercoat layer configuration. The two-layer undercoat comprises an electron transporting layer (ECL) having electroconducting particles dispersed or contained therein, and an interfacial layer (IFL) thereover. The ECL can suppress plywood. Excellent dispersion quality can be achieved, in embodiments. The IFL can serve as a hole-blocking layer, in embodiments. In embodiments, a two-layer undercoat structure has demonstrated extended photoreceptor life, and has eliminated large black spot detection primarily due to penetration of foreign materials such as carbon fibers, into the photoreceptor. In addition, the undercoat (ECL) can suppress plywood. Further, excellent dispersion quality can be achieved, in embodiments. The preparation of the undercoat is relatively simple and is prepared by mixing without any milling process. Moreover, the photoreceptor has humidity-independent performance, excellent durability, and the ability to achieve a wide range of surface electrical resistivity.